Apparatus for zone refining elongated bodies of metal



Jan- 29 1953 J. o. HINKLE ETAL 31,076,049 A APPARATUS FOR ZONE REFINING ELONGATED BODIES OF' METAL Filed April 4. 1961 5 SheetS-Shee'b 1 Jan. 29, 1963 J. o. HINKLE ETAL 3,076,049

APPARATUS FOR ZONE REFINING ELONGATED BODIES OF METAL Filed April 4'. 1961 5 Sheets-Sheet 2 FIA-INT1 INH L u ,1, l www n In U h JIM' W Zi/VEN 'raras' :../.J-/NKLIE' J; amm/LLB@ h l Jan. 29, 1963 J. O. HlNKLE ETAL Filed April 4. 1961 5 Sheets-Sheet 3 ngz:

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APPARATUS FOR ZONE REFINING ELONGATED BODIES 'OF METAL Filed April 4, 1961 5 Sheets-Sheet 4 MMI e7 @5. 'Mlm HW E; 77::

a ZI/VEN TDI- v1.5 9/ 90 mH//v/@E 5:: Quim/@E551 Jan. 29, 1963 J.o.H1NKLE ETAL APPARATUS FOR ZONE REFINING ELOGATED BODIES OF METAL 5 Sheets-Sheet 5 Filed April 4, 1961 we... N D n MH MN/n i VMM) D N l T lahm! T Q/.H u MNM i u? w H WN mN mw lnw@ United States Patent O 3,676,049 APPARATUS FOR ZNE RENNEN@ ELONGATED BDHES @F METAL .l ames Hinkle, Emmaus, and Robert K. Miller and .lack

J. Monahan, Allentown, Pa., assignors to Western Electrie Company, Incorporated, New York, NY., a corporation of New York Filed Apr. 4, 1961, Ser. No. H0577 17 Ciams. (Cl. 13-11) This invention relates to apparatus for zone refining elongated bodies of metal, particularly elongated silicon bodies.

Silicon wafers used in the manufacture off semi-conductor devices lare produced from silicon rods, but in order lt-hat the semi-'conductor devices may function most efiriciently, the rods from which the silicon wafers are produced, must be of sufficient purity.

An object of the present invention is an apparatus which is highly efficient in zone refining elongated bodies of metal.

In accordance with fthe object, the .apparatus comprises a vacuum chamber in which fan induction heating coil is mounted and a chuck for supporting lan elongated body of metal is mounted on a spindle disposed in axial alignment with the coil, While means is provided to impart movement to the spindle to move the body of metal at a lpredetermined speed through the coil.

More specifically, the apparatus includes spaced chucks for connection with both ends of the elongated body of metal, that is, -chucks having individual moving means including spindles for supporting the chucks, motors for rotating the spindles simultaneously, a main drive connected to lboth moving means, to move the elongated body of metal at a predetermined speed relative to the heating coil with associate drives for the moving means interposed between the main drive and the moving means, to cause variation in the driving speed of each moving means, to result in uniform thinning or broadening the elongated body of metal. AThe associate drives are connected to the main 4drive through differenti-al units adapted to condition the main drive, to move the spindles at like known speeds whenthe associate drives are cle-energized and to condition the main drive through either or both differential units to drive the spindles at greater or slower speeds selectively to control the movement of the elongated body of metal through the coil to create controlled variations in the size of the-body of metal. Other objects and advantages will be apparent from the following detailed description when considered in conjunction with the accompanying drawings wherein:

PG. l is `a side elevational view of a portion of the apparatus including the main and associate drives;

FG. 2 is fa front elevational view of an upper portion of the apparatus;

' FIG. 3 is a `front elevational view shown partially in section of a lower portion of the apparatus;

FIG. 4 is a front elevation-al view of the structure shown in 4 4 of FIG. 1 with theV associate drives removed;

FIG. 5 illustrates the necessary positioning of FIGS. 2, 3, and 4 to show the complete apparatus;

FIG. 6 is a schematic isometric lview of one of the differential units; tan-d FIGS. 7, 8, 9, and l0 are schematic illustrations of the actions of the apparatus for movement o-f the elongated body of metal relative to the heating coil.

After FIGS. 2, 3, and 4 have been positioned to illustrate Vthe complete apparatus, it will be noted that a central portion of the apparatus includes a vacuum chamber Ztl provided with a door 21 secured in place by clamps ice 22 and removed during unloading and loading of the work. A heat induction or radio frequency coil 23 is mounted centrally of the vacuum chamber and is of a contour to receive an elongated body of metal 24.

in the present instance, this is a silicon body 1/2" in diameter iand l in length. Hollow chucks 2S and 26 are adapted to receive the ends of the body 24 and are provided with suitable means such as set screws 27 and 2S to secure the ends of the work in the chucks. The chucks 25 and 26 are provided with identical moving means indicated generally at 29 and 30. Any description of the movin-g means 3i) will apply to both units.

In the HG. 3 portion of the apparatus, the chuck 26 is ixedly mounted on the upper end of a spindle 31 which extends freely through a hollow threaded shaft 32 and through an outer sleeve 33 where its outer end is connected to ya motor 34 of a type adapted to rotate its spindle at a definite slow speed simultaneously with the motor 34 of the moving means 29 so that both spindles 31 of the moving ymeans 29 and 30 will be rot-ated simultaneously at the same speeds and in the same direction. The purpose of the motor 34 is to rotate the Work or the elongated Ibody of metal in the coil 23 to assure uniform heat-ing of the successive floating zones of the body of metal moving through the coil 23.

The outer sleeve 33 has `a nut or internally threaded element 3o mounted in the end thereof opposite the end supporting the motor 34 for operative engagement with the threaded shaft 32. Furthermore, the outer sleeve 33 is positioned to move in a hollow portion 37 of a housing 38 which is fixed to a casing 39, the latter being secured to la bracket 4G which supports the vacuum charnber and both moving means 29 and Sil. The sleeve 33 supports a projection 33 positioned to ride in an elongated slot 38 of the housing 3S to hold the sleeve against rotation. A vcam il mounted on each outer sleeve 33 is positioned to engage series of switches 42, 43, 44, 45, d6, 47, 43, and 49 which serve in the operation of the apparatus, mainly to control movements of the chucks 25 and 26 and to assure stopping of the movements thereof prior to interference with the coil 23 or the supporting structures `at the opposite ends of the vacuum chamber.

Each moving means 29 and 3d has a worm gear Si. iixedly mounted on its threaded shaft 32 and supported by bearings SZ in the casing 39, and 53 in the housing 38. A wor-m :3d 4is rotatably `mounted in each casing 39 and interengages its respective worm gear 5l. Each worm 5d is provided with a shaft 5S coupled at S6 to a shaft 57. in the present illustration, the shafts 57 may be connected to either a main drive or motor SS or a rapid return drive or motor '59 through their respective clutches oli and 6i. Helical gears 62 mounted on the shafts 57 are connected to helical gears 63 mounted on shafts o4 of the output portions of clutches 6i. The shafts 57 extend to and constitute the output shafts of clutches titi.

At this point, it should be understood that suitable electrical circuits may be provided for the main and return `drives 53 and 59 and that these circuits may have the conventional electrical controls for the clutches 6% and 6l, which may be suitable magnetic clutches, so that only one of the motors S8 and 59 may -be energized at one time, that v/hen that motor is energized, its respective clutch will be engaged and when that motor is deenergized, its respective clutch will be dis-engaged. The rapid speed return drive or motor 59 has shafts o3 and 69 extending from opposite ends thereof -to the input portions of their clutches 6l.

Attention is now directedto FlGS. l and 3 illustrating the main drive or motor 58 having shafts 7o extending fromv opposite ends thereof, these shafts being connected at 7G to input shafts 67 of differential units 71. The differential units are identical With the exception that they extend in yopposite directions. The differential unit, Shownln FIG. 6, illustrates the input shaft 67 extending throughv a hollow shaft 72' and into a cage of the differential where it has a gear 73 mounted thereon. The cage of the differential is composed of head portions 74 secured together and' supported in their relative positions by a plurality of rods or spindles 75. An output shaft 77 of` the differential has a gear 7S, similar in size to the gear 73, mounted on its inner end. A pair of gearsl '79` and Sil, mounted on Ia hollow shaft d1, is rotatably supported on one of the 4rods 75 while another pair of gears 82 and 83, mounted on a ho1lowshaft84,is rotatably supported on another of the rods 7S.. The pairs of.

gears are positioned and maintained in these respective positionsso that gear 79 will interengage gear 73, gears: 86' and? 82 will interengage each' other, and gear 83 will4 interengage the gear '78;` Thecage xedy to the hollowf shaft 72 is under the control. of a beveled gear S5 which is fixed' to the hollow shaft and interengagesu a beveled` gear 8o. The output shafts 77 are connected through- 'couplingsA 8Std-input shafts 90 of speed reducing units; 91.

The beveled gears S6. are mounted on output shafts 92 of' speedy reducing units 93 of auxiliary drives'or motors 94;-and 95. The motors 94 and 95v are included inv cireui'ts from line 916,Y through their individual switches 97 'and 93. The switches, schematically illustrated in FIG. l, are adapted to de-energ-ize either associate drive 94. or '95, to drive these motors simultaneously in like or reverse directions andthrough the aid of additional controls, such as potentiometers 99' and 100, thespeeds of the associate drives may bev identical or variable;`

Operation Through the controls of the associate drives 94 `and 95, lthe chucks 25. and 26 may be located relative to each other irl the vacuum chamber so that after the cover 2,1 has been removed and the holding means or set screws- 27 and ii have been loosened,the chucks may be moved relative to each other to permit removal of arened body ofmetal 241 and the insertion of another to be refined as illustrated, for example, in FIG. l0. Through this or other suitable control means, the chucks 25 and 26 may bev moved toward each other during the mounting of a new workpiece in the chucks and after the ends thereof in the chucks, the chucks with the workpiece may be located at the starting position shown in FIGS. 2 and 7.

lf desired, during the first series of movements ofthe work through the coil in the feeding direction which, in the present instance, is upwardly, the control means may be set at the speed desired. The upward or treating movement ofV the apparatus through. the main. drive is variable between .0001 and .0015 of an inch perV second but is set at the selected speed. As the work moves relative 'to the coil, there is produced a floating zone in the work in the area of the coil where the metal in this area is molten. and. is supported by surface tension. Therefore, if it is desirable4 to bring about thinning or broadening of the contour of `the work or the bar of metal,l it is necessary that this be done in such a manner that the thinning or 4broadening effects may be produced by the minute controlling of varying speeds extending from the main drive or motor 5,8 through to the worms 54, the worm gears 51, the threaded shafts 32, the internally threaded elements 36 the external sleeves 33, and back through the spindles 31 to the chucks 25 and 26. As an example, with the associate drives 94 and 95 de-energized, they will function to hold the cages of their differentials 71 stationary and, as a result, a setting of a control for the main drive to bring about 10 revolutions per minute of" the input shafts 67, will result in l` revolutions of the output shafts 77 and through. the speedr reducing units 9i, theclutchesjt `and onto the ,moving means 29 and 3i), to

move the chucks 25 and 26 in unison so that they will carry out their separate functions of,l supporting the upper and lower ends of the work with the oating Zone of the work continuing as the work moves through the heating coil 23.

As another example, ifeither or both associate drives 94 and 95 should rotate its cage of its respective differential 71 in the opposite direction of the input shaft one revolution per minute, there will. be. 12 revolutions perk minute of thev output shaft 77 to every l() revolutions per minute of the input shaft 67. In following this. example, it is apparent that thede-energizatiou yof one of the associate power units 9d or 95 will causait to hold its differential cage stationary while the other is rotating its differential cage one revolution per minute in the opposite direction ofits input shaft, to cause aY constant knowny variation in the speeds ofl themoving'means 29 and'v 3h' to bringgabout a thinning,A result to the work.

As a further example; if either associate drive 940195 should cause rotation of itsdifferential cage one revolution per minute in thesan'xedirection as the direction ofrotation of the input shaft,y the; rotationy o fthe output shaft 77 would be onlyY revolutions percminuteas: compared to the l() revolutions perminute,of-`itsinputrshaft'67. This illustrates the possibility" of moving the4A work ata controlled slower rate when both associate drives-94 Vand 95 are moving their'differential'A cages at like speeds to produce varied speeds of' longitudinalmovementr of the work throughthe heatingcoil, and if'one of the associate drives should be held de-energized to holdl its differential' cage stationary, while thel other associate'drive bringsl about a slower drive for the output shaft 77, then there will result a broadening of the workl through thesuccessive iifoating zonesr moving through the coil 33. Also, these varying speeds may bel accentuated bythe driving of the motors in directionsl to cause faster results inv the thinning and broadening actions. Regardless-of how the thinningv and broadening' actions are produced andE the extremity of their variations, these changes occur gradually during the slow advancementY ofthe oating-zone-and during anyone, any'number or all the repeated movements of the body of metal through the coil to prod-ucea refined body of metalv of a predeterminedl cross-sectional contour throughout its length.

It is to be understoodthat the above described arrangements' are, simply illustrative of they application of the principlesv of the invention; Numerous other arrangements may be readily devisedf by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

Y 1. An apparatus for zone refining an elongated body of metal comprising an elongated vacuum chamber, aligned chucks disposed in the vacuum chamber for receiving opposing ends of -a body of metal, means to secure the ends of the bodyof metal in the chucks, an induction heating coil mounted in the vacuum chamber concentric with the body of metal, axially aligned spindles for the chucks extendingy through opposing ends of the vacuum and fixed to their respective chucks, separate means to move the spindles with their chucks axially to move the body of metal in one direction from a starting position through the coil lat a predetermined speed, a forward drive adapted forY connection with the separate moving` means, and an energizable auxiliary drive operatively connected intermediate the forward drive and one of the moving means to vary the speed'of axial movement of its spindle and chuck relative to the other spindle and chuck.

2. An apparatus according to claim l in which the operative connection between the` forward 4drive and the one of the moving means is a differential through which the speed of the moving means dependson the energization and de-energization of the auxiliary drive.

A3. An apparatusfor refining an elongated body of metal comprising a vacuum chamber, an induction heating coil mounted at a starting position in the chamber, a spindle extending into the chamber in axial alignment with the coil, a chuck mounted on an inner end of the spindle to receive one end of the body of metal, moving means for the spindle to cause axial movement of the body of metal relative to the coil, a main drive for the moving means, a differential having an input shaft operatively connected to the main drive, an output shaft operatively connected to the moving means, a cage rotatable axially of the shafts and intermediate gears movable with the cage and operatively connecting the shafts, and an auxiliary drive operatively connected to -the cage of the differential to control the effect of the main drive to cause the moving means to move the spindle at variable speeds.

4. An apparatus according to claim 3 in which means is adapted to cause the auxiliary drive to be inactive to thereby hold the cradle against rotation so that the output shaft will be driven at the same speed as the input shaft.

5. An apparatus according to claim 3 in which means is adapted to cause the auxiliary drive to rotate the cage in one direction so that the output shaft will be driven ata faster speed than the speed of the input shaft.

6. An apparatus according to claim 3 in which means is adapted to cause the auxiliary drive to rotate 4the cage in one direction so that the output shaft will be driven at a slower speed than the speed of the input shaft.

7. An apparatus according to claim l in which a reverse drive is adapted for connection with the separate moving means when the forward is disconnected therefrom to cause the spindles and chucks to return to their starting positions with the body of metal at a more rapid rate of speed.

8. An apparatus for zone reiining an elongated body of metal comprising an elongated vacuum chamber, an induction heating coil mounted at a refining position in the chamber, aligned chucks for gripping opposing ends of the body of metal aligned with the coil on opposing sides thereof in the chamber, axially aligned spindles extending through opposing ends of the chamber land having their inner ends ixed .to their respective chucks, separate means operable to move the spindles :axially with their chucks from starting positions to move the body of metal through the coil, a main drive adapted through clutch connections with the sperate moving means to move the spindles axially simultaneously to keep the chucks spaced the same distances apart during rening of the body by melting successive portions thereof during the intervals they are located in the rening position.

9. An apparatus according to claim 8 in which a rapid return drive is operable through clutch connections with the separate moving means when the clutch connections for the main drive are rendered ineffective to rapidly return the chucks to their starting positions.

10. An apparatus according to claim 8 in which the main drive is a main motor having two shafts, differentials having input shafts connected respectively to the shafts of the main motor, output shafts operatively connected to their respective separate moving means and cages having gears operatively connecting their input and output shafts, and auxiliary motors operatively connected respectively to the cages of the differentials.

1l. An apparatus according to claim 10 in which means is operable to cause de-energization ofthe auxiliary motors to cause them to hold the differential cages stationary so that the speeds of the output shafts will equal the speeds of the input shafts.

12. An apparatus according to claim 10 in which means are operable to cause energization of the auxiliary motors to cause rotation of the cages to cause the output shafts to be driven at faster speeds than the input shafts.

13. An apparatus according to claim l0 in which means are operable to cause energization of the auxiliary motors to canse rotation of the cages to cause the output shafts to be driven at slower speeds than the input shafts.

14. An apparatus according to claim 10 in which means are operable to cause energization of one of the auxiliary motors in a given direction to cause movement of its chuck relative to the other chuck to cause variation in the thickness of the body of metal.

15. An apparatus according to claim 1G in which means are operable to cause energization of either auxiliary motor in either reversible directions to cause advancement of the chucks at predetermined variable speeds to control predetermined variations in the thickness of the bar of metal.

16. An apparatus according to claim 10 in which means are actuable to energize the auxiliary motors at like and variable speds to drive the output shafts at like and variable speeds to control the speeds of movement of the chucks.

17. An apparatus according to claim 10 in which each auxiliary motor is provided with switch means to deencrgize or energize in either direction, and means to vary the speed of rotation of each auxiliary motor to vary the speed of the differential cage and the output shaft thereof.

References Cited in the iile of this patent UNITED STATES PATENTS 2,992,311 Keller July 11, 1961 

1. AN APPARATUS FOR ZONE REFINING AN ELONGATED BODY OF METAL COMPRISING AN ELONGATED VACUUM CHAMBER, ALIGNED CHUCKS DISPOSED IN THE VACUUM CHAMBER FOR RECEIVING OPPOSING ENDS OF A BODY OF METAL, MEANS TO SECURE THE ENDS OF THE BODY OF METAL IN THE CHUCKS, AN INDUCTION HEATING COIL MOUNTED IN THE VACUUM CHAMBER CONCENTRIC WITH THE BODY OF METAL, AXIALLY ALIGNED SPINDLES FOR THE CHUCKS EXTENDING THROUGH OPPOSING ENDS OF THE VACUUM AND FIXED TO THEIR RESPECTIVE CHUCKS, SEPARATE MEANS TO MOVE THE SPINDLES WITH THEIR CHUCKS AXIALLY TO MOVE THE BODY OF METAL IN ONE DIRECTION FROM A STARTING POSITION THROUGH THE COIL AT A PREDETERMINED SPEED, A FORWARD DRIVE ADAPTED FOR CONNECTION WITH THE SEPARATE MOVING MEANS, AND AN ENERGIZABLE AUXIALIARY DRIVE OPERATIVELY CONNECTED INTERMEDIATE THE FORWARD DRIVE AND ONE OF THE MOVING MEANS TO VARY THE SPEED OF AXIAL MOVEMENT 